Process debugging affects the laser cutting quality


With the rapid development of laser cutting technology, laser cutting has been widely used in sheet metal processing, automobile manufacturing, engineering machinery, fitness equipment and other industries. So how to cut high-quality products, in addition to the quality of the laser cutting machine, process debugging is also a key factor! Next, we will take the stainless steel thick plate as an example to briefly analyze the settings of each element of the cutting process.

To Cutting process elements:

01. Nozzle selection

The diameter of the nozzle determines the shape of the gas flow entering the incision, the gas diffusion area, and the gas flow rate, thereby affecting the stability of the melt removal and cutting. The air flow into the incision is large, the speed is fast, and the position of the work piece in the air flow is appropriate, the stronger the jetting ability to remove the molten material. Under a fixed flow, different nozzle sizes, the thicker the stainless steel that monitors the air pressure, the larger the nozzle selection should be, the larger the proportional valve setting, and the larger the flow, can the pressure be ensured and the normal section effect can be cut.

02. auxiliary gas selection and gas purity

Various auxiliary gases are often used in stainless steel laser cutting processing, such as oxygen, nitrogen, air, etc. Different gas types are used, and the effect of cutting sections is different. Oxygen is a black section, air is light yellow, and nitrogen can keep the original color of stainless steel from being oxidized. Nitrogen is the preferred auxiliary gas for stainless steel cutting.

To Recommended oxygen and nitrogen purity:

【Oxygen】Advantages: high cutting speed, able to cut thick sheets. Purity suggestion: ≥99.999%

【Nitrogen】 Advantages: Avoid oxidation of the cutting edge, so the work piece does not need to be reprocessed. Purity recommendation: ≥99.995%  

03. focal spot position In order to ensure the cutting effect and protect the nozzle from damage, it is necessary to do a coaxial test before cutting to ensure that the nozzle is coaxial with the laser output beam. Test method: Attach the transparent tape to the nozzle outlet end surface, adjust the laser output power to punch, observe whether there is a center hole and the position of the center hole on the transparent tape, adjust the adjustment screw on the handle of the mirror cavity synchronously, until the laser is on The hole punched in the scotch tape coincides with the center of the nozzle.

The focus is different, the thickness, material, and quality that can be cut are also different. Different materials and thicknesses need to be adjusted to different focus points. Before cutting, the actual zero focus is measured, and the test and analysis of the cutting process parameters can be carried out with the zero focus as the benchmark. The negative defocus is the main process selection direction for stainless steel cutting.

04. Laser frequency adjustment and the influence of duty cycle on cutting quality The effect of frequency change on stainless steel thick plate cutting: the frequency is reduced from 500-200Hz, the cutting section effect becomes finer, and the layering is gradually improved. When the frequency is set to 100Hz, it cannot be cut and the blue light is reversed. Through frequency change, find the best frequency range. In order to ensure the best cutting section, the number of pulses must be perfectly matched with the energy of a single pulse.

Generally speaking, precision work, nozzle height, machine motion parameters, motion acceleration, operating speed, material quality, etc. have an important impact on the cutting results. The application field of laser cutting will be further expanded in the future.